Management of Dermatomyositis

Introduction

I. Initial Assessment Before Starting Treatment (1 mark)

• Comprehensive history, physical examination (including pelvic exam in women)
• CBC, LFT, RFT, urinalysis, stool occult blood
• CT chest/abdomen/pelvis; colonoscopy
• PET scan in selected cases
• Age/sex/ethnicity-appropriate screening (mammogram, Pap smear, nasopharyngoscopy in Asians for NPC)
• Autoantibody panel (anti-TIF1-γ / anti-NXP-2 = high malignancy risk; anti-Jo-1 = ILD risk; anti-MDA5 = rapidly progressive ILD)

II. General Measures (0.5 mark)

• Photoprotection: Broad-spectrum sunscreen SPF ≥30 (with UVA cover) applied daily; sun-protective clothing, hats. Critical because DM is photosensitive and UV exacerbates both skin and muscle disease.
• Rest during active disease with graded physical therapy and physiotherapy once muscle inflammation is controlled, to prevent contractures and improve strength.
• Osteoporosis prophylaxis: Calcium + Vitamin D supplementation; bisphosphonate if long-term corticosteroids are anticipated.
• Monitoring: Repeat CK/aldolase every 2–3 months to guide therapy.

III. Treatment of Muscle Disease (Myositis) (3 marks)

First-Line: Systemic Corticosteroids

• Dose: 1 mg/kg/day (max 60–80 mg/day) orally; continued until muscle strength improves and enzymes normalize
• CK and AST/ALT return to normal as remission occurs
• Taper: Reduce to 0.5 mg/kg/day (single morning dose) by 6–8 months
• Disease under control rapidly in 2–4 weeks if CK mildly elevated; if CK >1000 U/L, use IV pulse methylprednisolone (1 g/day × 3 days) plus early steroid-sparing agent
• Monitoring for steroid toxicity: Hyperglycemia, hypertension, GI ulceration, adrenal suppression, cataracts, avascular necrosis

Second-Line: Steroid-Sparing Agents (Immunosuppressants)

IV. Treatment of Skin Disease (2 marks)

Topical Therapies

• Topical corticosteroids (mid-to-high potency): for limited cutaneous disease, pruritus
• Topical tacrolimus (0.1%): Steroid-sparing for facial lesions; calcineurin inhibitor

Systemic Therapies for Cutaneous DM

• Hydroxychloroquine: 5 mg/kg/day divided (up to 200 mg BD) — standard of care for skin lesions; note higher rate of cutaneous drug eruptions in DM (~25%) compared to SLE. If inadequate, add quinacrine 100 mg/day (triple therapy with chloroquine + quinacrine also used)
• IVIG (intravenous immunoglobulin): 2 g/kg/month (0.5–1 g/kg/day × 2 days/month) — beneficial particularly for skin disease; Level 1 evidence; also effective in refractory anti-MDA5 disease with rapidly progressive ILD. Risks: thromboembolism (DVT, PE, MI, stroke) — consider concomitant aspirin
• Dapsone: Useful for cutaneous DM (case reports and series)
• Low-dose methotrexate: Effective for recalcitrant skin disease

V. Treatment of Refractory/Severe Disease (2 marks)

• Rituximab: Anti-CD20 monoclonal antibody; 375 mg/m² × 4 weekly doses or 1 g × 2 doses; improves muscle disease; less effective for skin disease; promising in refractory juvenile DM
• Tacrolimus (oral): Particularly effective in severe refractory disease; also useful in anti-MDA5 DM with ILD
• Cyclosporine: 2.5–5 mg/kg/day; used in severe/refractory cases
• Cyclophosphamide: Reserved for life-threatening ILD or vasculitis
• JAK inhibitors (Tofacitinib 5–10 mg/day; Ruxolitinib): Dramatic benefit reported in refractory DM; rationale — type I IFN/JAK-STAT pathway is central to DM pathogenesis; particularly for refractory cutaneous disease
• Infliximab / Anti-TNF-α: Rapidly effective for myositis in some patients; use with caution — anti-TNF therapy can itself induce DM and cause flares
• Leflunomide: Adjuvant immunomodulatory therapy (used in RA); effective in DM
• Anakinra, tocilizumab, abatacept: Emerging biologics in small series

VI. Treatment of Complications (1 mark)

Calcinosis Cutis

• Diltiazem: Most commonly used
• Aluminum hydroxide, bisphosphonates (alendronate), probenecid, colchicine, low-dose warfarin, sodium thiosulfate
• Surgical excision: For large, painful, or functionally limiting deposits
• Prevention: Early, aggressive therapy in juvenile DM reduces calcinosis risk

Interstitial Lung Disease (ILD)

• MMF preferred steroid-sparer (antifibrotic effect)
• Cyclophosphamide or rituximab for rapidly progressive ILD (esp. anti-MDA5 DM)
• Pirfenidone/nintedanib under investigation

Dysphagia

• Nasogastric/PEG feeding in severe cases
• IVIG, IV methylprednisolone for acute pharyngeal myositis

VII. Management in Special Situations (0.5 mark)

Juvenile DM

• IV/oral pulse methylprednisolone for acute management
• Methotrexate or IVIG may be equally effective, possibly avoiding corticosteroids
• Rituximab promising in refractory cases
• Early aggressive treatment reduces calcinosis

Pregnancy

• Topical corticosteroids and topical calcineurin inhibitors are first-line
• Systemic corticosteroids, hydroxychloroquine, and azathioprine are acceptable when necessary
• Avoid methotrexate, MMF, cyclophosphamide (teratogenic)

Cancer-Associated DM

• Treat underlying malignancy — DM course does not always parallel the malignancy
• Use immunosuppression strategies similar to non-paraneoplastic DM (corticosteroids, methotrexate, azathioprine, MMF, IVIG, rituximab)

VIII. Monitoring and Follow-Up (implied)

• CK/aldolase every 2–3 months
• Annual malignancy surveillance (risk remains elevated >5 years)
• DEXA scan for osteoporosis
• PFTs annually (ILD monitoring)
• Ophthalmologic review for hydroxychloroquine toxicity (annual after 5 years)

Summary Table: Therapeutic Ladder for DM

Prognosis Note

• Are you asking for alopecia mucinosa alone (a more detailed/expanded answer than the 5-mark version I gave yesterday)?
• Or is this a list like "A) Alopecia mucinosa / B) [topic] / C) [topic]..." for a new set of answers?